Phenanthroline derivative and use thereof

ABSTRACT

The present invention discloses a phenanthroline derivative is represented by the following formula(I), the organic EL device employing the phenanthroline derivative as hole blocking electron transport material, electron transport material can display good performance like as lower driving voltage and power consumption, increasing efficiency and half-life time. 
     
       
         
         
             
             
         
       
     
     wherein Ar, m, n, p and R 1  to R 4  are the same definition as described in the present invention.

FIELD OF INVENTION

The present invention generally relates to a phenanthroline derivativeand organic electroluminescent(herein referred to as organic EL) deviceusing the derivative. More specifically, the present invention relatesto the derivative having general formula(I), an organic EL deviceemploying the derivative as hole blocking electron transportmaterial(herein referred to as HBETM), electron transportmaterial(herein referred to as ETM).

BACKGROUND OF THE INVENTION

Organic electroluminescent(organic EL) is a light-emitting diode (LED)in which the emissive layer is a film made by organic compounds whichemits light in response to an electric current. The emissive layer oforganic compound is sandwiched between two electrodes. Organic EL isapplied in flat panel displays due to their high illumination, lowweight, ultra-thin profile, self-illumination without back light, lowpower consumption, wide viewing angle, high contrast, simple fabricationmethods and rapid response time.

The first observation of electroluminescence in organic materials werein the early 1950s by Andre Bernanose and co-workers at the Nancy-University in France. Martin Pope and his co-workers at New YorkUniversity first observed direct current(DC) electroluminescence on asingle pure crystal of anthracene and on anthracene crystals doped withtetracene under vacuum in 1963.

The first diode device was reported by Ching W. Tang and Steven VanSlyke at Eastman Kodak in 1987. The device used a two-layer structurewith separate hole transporting and electron transporting layersresulted in reduction in operating voltage and improvement of theefficiency, that led to the current era of organic EL research anddevice production.

Typically organic EL is composed of layers of organic materials situatedbetween two electrodes, which include a hole transporting layer(HTL), anemitting layer(EML), an electron transporting layer(ETL). The basicmechanism of organic electroluminescence involves the injection of thecarrier, transport, recombination of carriers and exciton formed to emitlight. When an external voltage is applied to an organic light-emittingdevice, electrons and holes are injected from a cathode and an anode,respectively, electrons will be injected from a cathode into aLUMO(lowest unoccupied molecular orbital) and holes will be injectedfrom an anode into a HOMO(highest occupied molecular orbital). When theelectrons recombine with holes in the emitting layer, excitons areformed and then emit light. When luminescent molecules absorb energy toachieve an excited state, an exciton may either be in a singlet state ora triplet state depending on how the spins of the electron and hole havebeen combined. 75% of the excitons form by recombination of electronsand holes to achieve a triplet excited state. Decay from triplet statesis spin forbidden. Thus, a fluorescence electroluminescent device hasonly 25% internal quantum efficiency. In contrast to fluorescenceelectroluminescent device, phosphorescent organic light-emitting diodesmake use of spin-orbit interactions to facilitate intersystem crossingbetween singlet and triplet states, thus obtaining emission from bothsinglet and triplet states and the internal quantum efficiency ofelectroluminescent devices from 25% to 100%.

Recently, a new type of fluorescent organic EL incorporating mechanismof thermally activated delayed fluorescence(TADF) has been developed byAdachi and coworkers is a promising way to obtain a high efficiency ofexciton formation by converting spin-forbidden triplet excitons up tothe singlet level by the mechanism of reverse intersystemcrossing(RISC).

The phosphorescent organic EL utilizes both triplet and singletexcitons. Cause of longer life time and the diffusion length of tripletexcitons compared to those of singlet excitons, the phosphorescentorganic EL generally need an additional hole blocking layer(HBL) betweenthe emitting layer(EML) and the electron transporting layer(ETL) or theelectron transporting layer with hole blocking ability instead oftypical ETL. The purpose of the use of HBL or HBETL is to confine therecombination of injected holes and electrons and the relaxation ofcreated excitons within the EML, hence the device's efficiency can beimproved. To meet such roles, the hole blocking materials must haveHOMO(highest occupied molecular orbital) and LUMO(lowest unoccupiedmolecular orbital) energy levels suitable to block hole transport fromthe EML to the ETL and to pass electrons from the ETL to the EML, inaddition, the good thermal and electrochemical stability of thematerials are also needed.

Currently, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),bathophenanthroline(Bphen) have been used as the typical materials forthe HBL and HBETL of phosphorescent OLED. However, phenanthrolinederivatives exhibit lower Tg(Bphen:55° C., BCP:65° C.), lowerheat-resistant(Td: /Weight loss <0.5% at 240° C. for Bphen and 260° C.for BCP). It's difficult to operate under deposition process and itsdevices show lower stability and short half-life time. U.S. Pat. No.7,119,204 disclose a series of substituted-phen anthroline derivatives,as electron-transporting materials. U.S. Pat. No. 7,282,586 disclose aspecific phenanthroline derivative2,9-bis(5-(biphenyl-4-yl)-1,3,4-oxadiazol-2-yl)-1,10-phenanthroline, asan electron transporting material, compare with conventional2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), the drive voltageis decreased from 8V to 7V at 2000cd/m ², and higher current efficiencyis achieved. U.S. Pat. No. 7,754,348 disclose a series of2,9-substituted phenanthroline derivatives as electron transportingmaterial, higher operate life time and higher luminance than comparableexample 1-3 and Alq3 has also been achieved at a driving voltage of 5V.U.S. Pat. No. 7,982,213 disclose a series of aryl substitutedphenanthroline, a phosphorescent organic EL using the phenanthrolinecompound as HBETL provided high efficiency and a high luminance and hasa high long-term durability. U.S. Pat. No. 8,114,529 disclose a seriesof bis-phenanthroline skeleton compounds, by using phenanthrolinecompounds as HBETL, a phosphorescent organic EL having low drivingvoltage and excellent durability.

There continues to be a need for organic EL materials which is able toefficiently transport electrons and block holes, with good thermalstability and high emitting efficiency. According to the reasonsdescribed above, the present invention has the objective of resolvingsuch problems of the prior-art and offering a light emitting devicewhich is excellent in its thermal stability, high luminance efficiency,high luminance and long half-life time. The present invention disclose anovel phenanthroline derivative having general formula(I), used as holeblocking electron transport material(HBETM) or electron transportmaterial(ETM) have good charge carrier mobility and excellentoperational durability can lower driving voltage and power consumption,increasing efficiency and half-life time of organic EL device.

SUMMARY OF THE INVENTION

Provided a phenanthroline derivative can use as hole blocking electrontransport material(HBETM) or electron transport material(ETM) fororganic EL device. The phenanthroline derivative can overcome thedrawbacks of the prior materials like as lower efficiency, half-lifetimeand higher power consumption.

An object of the present invention is to provide the phenanthrolinederivative which can be used as hole blocking electron transportmaterial(HBETM) or electron transport material(ETM) for organic ELdevice.

The present invention has the economic advantages for industrialpractice. Accordingly the present invention, the phenanthrolinederivative which can be used for organic EL device is disclosed. Thementioned the phenanthroline derivative represented by the followingformula(I):

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 show one example of organic EL device in the present invention,and 6 is transparent electrode, 13 is metal electrode, 7 is holeinjection layer which is deposited onto 6, 8 is hole transport layerwhich is deposited onto 7, 9 is fluorescent or phosphorescent emittinglayer which is deposited onto 8, 10 is hole blocking layer which isdeposited onto 9, 11 is electron transport layer which is deposited onto10, 12 is electron injection layer which is deposited on to 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

What probed into the invention is the phenanthroline derivative andorganic EL device using the phenanthroline derivative. Detaileddescriptions of the production, structure and elements will be providedin the following to make the invention thoroughly understood. Obviously,the application of the invention is not confined to specific detailsfamiliar to those who are skilled in the art. On the other hand, thecommon elements and procedures that are known to everyone are notdescribed in details to avoid unnecessary limits of the invention. Somepreferred embodiments of the present invention will now be described ingreater detail in the following. However, it should be recognized thatthe present invention can be practiced in a wide range of otherembodiments besides those explicitly described, that is, this inventioncan also be applied extensively to other embodiments, and the scope ofthe present invention is expressly not limited except as specified inthe accompanying claims.

In a first embodiment of the present invention, the phenanthrolinederivative which can be used as hole blocking electron transportmaterial(HBETM) or electron transport material(ETM) for organic ELdevice are disclosed. The mentioned phenanthroline derivativerepresented by the following formula(I):

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.

According to the above-mentioned the phenanthroline derivativeformula(I), wherein Ar represented the follows:

According to the above-mentioned the phenanthroline derivativeformula(I) represented by the following formula(II) :

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.

According to the above-mentioned the phenanthroline derivativeformula(II), wherein Ar represented the follows:

In this embodiment, some phenanthroline derivatives are shown below :

Detailed preparation for the phenanthroline derivative in the presentinvention could be clarified by exemplary embodiments, but the presentinvention is not limited to exemplary embodiments. EXAMPLE 1-3 show thepreparation for examples of the phenanthroline derivative in the presentinvention. EXAMPLE 4 show the fabrication of organic EL device andI-V-B, half-life time of organic EL device testing report.

EXAMPLE 1 Synthesis of EX1 Synthesis of9-bromo-10-(naphthalen-1-yl)anthracene

A mixture of 40 g(119 mmol) of 9,10-dibromoanthracene, 20.5 g(119 mmol)of naphthalen-1-ylboronic acid, 1.38 g(1.2 mmol) of Pd(PPh₃)₄, 120 ml of2M Na₂CO₃, 200 ml of EtOH and 600 ml toluene was degassed and placedunder nitrogen, and then heated at 100° C. for 12 h. After finishing thereaction, the mixture was allowed to cool to room temperature. Theorganic layer was extracted with ethyl acetate and water, dried withanhydrous magnesium sulfate, the solvent was removed and the residue waspurified by column chromatography on silica to give product(19.2 g, 50mmol, 42%) as a yellow solid.

Synthesis of 4-(10-(naphthalen-1-yl)anthracen-9-yl)aniline

A mixture of 20 g(52.2 mmol) of 9-bromo-10-(naphthalen-1-yl)-anthracene,13.7 g(62.6 mmol) of4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline, 0.6 g(0.52 mmol)of Pd(PPh₃)₄, 52 ml of 2M Na₂CO₃, 150 ml of EtOH and 450 ml toluene wasdegassed and placed under nitrogen, and then heated at 100° C. for 12 h.After finishing the reaction, the mixture was allowed to cool to roomtemperature. The organic layer was extracted with ethyl acetate andwater, dried with anhydrous magnesium sulfate, the solvent was removedand the residue was purified by column chromatography on silica to giveproduct(12.8 g, 32.3 mmol, 62%) as a yellow solid.

Synthesis ofN-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-nitroaniline

A mixture of 10 g(25.3 mmol) of 4-(10-(naphthalen-1-yl)anthracen-9-yl)aniline, 6.3 g(25.3 mmol) of 1-iodo-2-nitrobenzene, 56.7mg(0.25 mmol) of Pd(OAc)₂, 4.86 g(50.6 mmol) of sodium tert-butoxide,400 ml of O-xylene was degassed and placed under nitrogen, and thenheated at 140° C. for 12 h. After finishing the reaction, the mixturewas allowed to cool to room temperature.

The organic layer was extracted with ethyl acetate and water, dried withanhydrous magnesium sulfate, the solvent was removed and the residue waspurified by column chromatography on silica to give product(4.44 g, 8.6mmol, 34%) as a brown solid.

Synthesis ofN1-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenylbenzene-1,2-diamine

A mixture of 10 g(19.3 mmol) ofN-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-nitroaniline, 3.24g(58 mmol) of iron powder, 200 ml of ethanol was degassed and placedunder nitrogen, and then heated at 80° C. for 30 min. 12.1 ml 37.5%(96.5mmol) of hydrochloric acid was then added, and then heated at 80° C. for12 h. After finishing the reaction, the mixture was allowed to cool toroom temperature. 13 ml of ammonia solution, 21.8 g(77.2 mmole) ofpotassium sodium tartrate, and 600 ml water was added, and then stir for30 min. The organic layer was extracted with dichloromethane and water,dried with anhydrous magnesium sulfate, the solvent was removed and theresidue was purified by column chromatography on silica to giveproduct(7.8 g, 16 mmol, 83%) as a brown solid.

Synthesis of2-(4-bromophenyl)-1-(4-(10-(naphthalen-1-yl)anthraces-9-yl)phenyl)-1H-benzo[d]imidazole

A mixture of 10 g(20.5 mmol) ofN1-(4-(10-(naphthalen-1-yl)-anthracen-9-yl)phenyl)benzene-1,2-diamine,4.56 g(24.7 mmol) of 4-bromo-benzaldehyde, 782 mg(4.1 mmol) ofp-toluenesulfonic acid, 200 ml of anhydrous toluene was degassed andplaced under nitrogen, and then heated at 110° C. for 12 h. Afterfinishing the reaction, the mixture was allowed to cool to roomtemperature. The organic layer was extracted with dichloromethane andwater, dried with anhydrous magnesium sulfate, the solvent was removedand the residue was purified by column chromatography on silica to giveproduct(3.74 g, 5.7 mmol, 28%) as a yellow solid.

Synthesis of 1-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole

A mixture of 5 g(7.67 mmol) of2-(4-bromophenyl)-1-(4(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-1H-benzo[d]imidazole,2.14 g(8. 4 mm ol) of4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane), 177 mg(0.15 mmol) of Pd(PPh3)4, 1.5 g(15.5 mmol) of potassium acetate, 100 mlof 1,4-dioxane was degassed and placed under nitrogen, and then heatedat 100° C. for 12 h. After finishing the reaction, the mixture wasallowed to cool to room temperature. The organic layer was extractedwith ethyl acetate and water, dried with anhydrous magnesium sulfate,the solvent was removed and the residue was purified by columnchromatography on silica to give product(3.1 g, 4.4 mmol, 58%) as ayellow solid.

Synthesis of EX1

A mixture of 3 g(8.2 mmol) of 2-chloro-4,7-diphenyl-1,10-phenanthroline,6.28 g(9 mmol) of 1-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole,189mg(0.16 mmol) of Pd(PPh₃)₄, 8.2 ml of 2M Na₂CO₃, 40 ml of EtOH and120 ml toluene was degassed and placed under nitrogen, and then heatedat 100° C. for 12 h. After finishing the reaction, the mixture wasallowed to cool to room temperature. The organic layer was extractedwith dichloromethane and water, dried with anhydrous magnesium sulfate,the solvent was removed and the residue was purified by columnchromatography on silica to give product(4.8 g, 5.3 mmol, 65%) as ayellow solid. MS(m/z ,FAB⁺):902.8; ¹H NMR (CDCl₃, 500 MHz): chemicalshift (ppm) 8.69(d, 2H), 8.49(d, 2H), 8.23(s, 1H), 8.17-8.11(d, 2H),7.89-7.83(m, 4H), 7.80-7.68(m, 6H), 7.65-7.49(m, 14H), 7.45-7.41(m, 2H),7.40-7.27(m, 9H).

EXAMPLE 2 Synthesis of EX6 Synthesis of 4,7-diphenyl-2-(4-(1-(4-(10-phenylanthracen-9-yl)phenyl)-1H-benzo[d]imidazol-2-yl)phenyl)-1,10-phenanthroline

1-(4-(10-phenylanthracen-9-yl)phenyl)-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazoleinstead of 1- (4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-(4-(4,4,5, 5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole,except for using the same method as in synthesis example 1, the desiredcompound of 4, 7-diphenyl-2-(4-(1-(4-(10-phenylanthracen-9-yl)phenyl)-1H-benzo[d]imidazol-2-yl)phenyl)-1,10-phenanthroline(4.3g, yield=62%) was obtained. MS(m/z ,FAB⁺):852.8; ¹H NMR (CDCl₃, 500MHz): chemical shift (ppm) 8.68(d, 2H), 8.50(d, 2H), 8.25(s, 1H),8.19-8.13(d, 2H), 7.91-7.82(m, 4H), 7.78-7.68(m, 6H), 7.65-7.48(m, 12H),7.46-7.42(m, 2H), 7.40-7.28(m, 9H).

EXAMPLE 3 Synthesis of EX12

Synthesis of 2-(4-(1-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-1H-benzo[d]imidazol-2-yl)phenyl)-4,7-diphenyl-1,10-phenanthroline

1-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazoleinstead of 1- (4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-2-(4-(4,4,5, 5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-1H-benzo[d]imidazole,except for using the same method as in synthesis example 1, the desiredcompound of -(4-(1-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-1H-benzo[d]imidazol-2-yl)phenyl)-4,7-diphenyl-1,10-phenanthroline(4.87 g, yield=66%) was obtained. MS(m/z ,FAB⁺):902.8; ¹H NMR (CDCl₃,500 MHz): chemical shift (ppm) 8.70(d, 2H), 8.51(d, 2H), 8.22(s, 1H),8.16-8.09(d, 2H), 7.88-7.83(m, 4H), 7.80-7.70(m, 6H), 7.65-7.51(m, 14H),7.47-7.41(m, 2H), 7.40-7.28(m, 9H).

General Method of Producing ORganic El Device ITO-coated glasses with9-12 ohm/square in resistance and 120-160 nm in thickness areprovided(hereinafter ITO substrate) and cleaned in a number of cleaningsteps in an ultrasonic bath(e.g. detergent, deionized water). Beforevapor deposition of the organic layers, cleaned ITO substrates arefurther treated by UV and ozone. All pre-treatment processes for ITOsubstrate are under clean room(class 100).

These organic layers are applied onto the ITO substrate in order byvapor deposition in a high-vacuum unit(10⁻⁷ Torr), such as: resistivelyheated quartz boats. The thickness of the respective layer and the vapordeposition rate (0.1˜0.3 nm/sec) are precisely monitored or set with theaid of a quartz-crystal monitor. It is also possible, as describedabove, for individual layers to consist of more than one compound, i.e.in general a host material doped with a dopant material. This isachieved by co-vaporization from two or more sources.

Dipyrazino [2,3-f: 2,3-]quinoxaline-2,3,6,7,10,11-hexacarbonitrile(HAT-CN) is used as hole injection layer in this organic EL device,N,N-Bis(naphthalene-1-yl)-N,N-bis(phenyl)-benzidine(NPB) is most widelyused as the hole transporting layer,10,10-Dimethyl-12-(4-(pyren-1-yl)phenyl)-10H-indeno[1,2-b]triphenylene(PT-312,US20140175384)is used as blue emitting host in organic EL device andN1,N1,N6,N6-tetram-tolylpyrene-1,6-diamine(D1) is used as blue guest;2-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-13-yl)-4,6-diphenyl-1,3,5-triazine(HB1),2-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-12-yl)-4,6-diphenyl-1,3,5-triazine(HB2) and HB3(see the following chemical structure) are used as holeblocking material(HBM);4,7-diphenyl-2-(411-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)-1,10-phenanthroline(ET1)and 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (ET2) areused as electron transporting material(ET1) to co-deposit with 5% Li, orco-deposit with 8-hydroxyquinolato-lithium(LiQ) in organic EL device forcomparison. The prior art of OLED materials for producing standardorganic EL device control and comparable material in this inventionshown its chemical structure as follows:

A typical organic EL device consists of low work function metals, suchas Al, Mg, Ca, Li and K, as the cathode by thermal evaporation, and thelow work function metals can help electrons injecting the electrontransporting layer from cathode. In addition, for reducing the electroninjection barrier and improving the organic EL device performance, athin-film electron injecting layer is introduced between the cathode andthe electron transporting layer. Conventional materials of electroninjecting layer are metal halide or metal oxide with low work function,such as: LiF, LiQ, MgO, or Li₂O. On the other hand, after the organic ELdevice fabrication, EL spectra and CIE coordination are measured byusing a PR650 spectra scan spectrometer. Furthermore, thecurrent/voltage, luminescence/voltage and yield/voltage characteristicsare taken with a Keithley 2400 programmable voltage-current source. Theabove-mentioned apparatuses are operated at room temperature(about 250C) and under atmospheric pressure.

EXAMPLE 4

Using a procedure analogous to the above mentioned general method,fluorescent blue-emitting organic EL device having the following devicestructure I and II was produced(See FIG. 1). Device I: ITO/HAT-CN (20nm)/NPB(110 nm)/PT-312 doped 5% D1(30 nm)/HBM/ETM doped 5% Li(35nm)/Al(160 nm). Device II: ITO/HAT-CN(20 nm)/NPB(110 nm)/PT-312 doped 5%D1(30 nm)/HBM/ETM co-deposit 50% LiQ(40 nm)/LiQ (1nm)/Al (160nm). TheI-V-B(at 1000nits) and half-life time of fluorescent blue-emittingorganic EL device testing report as Table 1 and Table2. The half-lifetime is defined that the initial luminance of 1000cd/m² has dropped tohalf.

TABLE 1 ETM doped Voltage Efficiency Half-life time HBM 5% Li (V) (cd/A)CIE (y) (hour) HB1 ET1 6.2 3.8 0.176 150 HB1 ET2 6.5 3.9 0.178 160 HB1EX1 4.8 5.5 0.172 350 HB1 EX6 4.5 4.9 0.173 280 HB1 EX12 4.5 6.3 0.173350 — EX12 4.6 6.0 0.172 300 HB2 EX1 4.0 6.5 0.173 450

TABLE 2 ETM co-deposit Voltage Efficiency Half-life HBM 50% LiQ (V)(cd/A) CIE (y) time (hour) HB3 ET1 7.0 4.6 0.189 180 HB3 ET2 6.6 4.30.188 160 HB3 EX1 5.8 6.2 0.181 480 HB3 EX6 4.9 5.1 0.180 360 HB3 EX124.3 6.6 0.181 450 — EX12 4.6 6.1 0.182 400 HB2 EX1 4.5 6.9 0.180 510

In the above preferred embodiments for organic EL device test report(seeTable 1 to Table 2), we show that the phenanthroline derivative with ageneral formula(I) used as hole blocking electron transport material orelectron transport material for organic EL in the present inventiondisplay good performance than the prior art of organic EL materials.More specifically, the organic EL device in the present invention usethe phenanthroline derivative with a general formula(I) as electrontransport material to collocate with hole blocking material such as HB1,HB2 and HB3 shown lower power consumption, higher efficiency and longerhalf-life time. Besides the organic EL device in the present inventionuse the phenanthroline derivative with a general formula(I) also can useas hole blocking electron transport material without collocate with holeblocking material and shown good performance than prior art of organicEL materials

To sum up, the present invention discloses a phenanthroline derivativewith a general formula(I) used as hole blocking electron transportmaterial or electron transport material for organic EL device. Thementioned phenanthroline derivative are represented by the followingformula(I)

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.

Obvious many modifications and variations are possible in light of theabove teachings. It is therefore to be understood that within the scopeof the appended claims the present invention can be practiced otherwisethan as specifically described herein. Although specific embodimentshave been illustrated and described herein, it is obvious to thoseskilled in the art that many modifications of the present invention maybe made without departing from what is intended to be limited solely bythe appended claims.

1. A phenanthroline derivative represented by the following formula(I) :

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.
 2. Thephenanthroline derivative according to claim 1, wherein Ar isrepresented by the following formulas :


3. The phenanthroline derivative according to claim 1, wherein thephenanthroline derivative formula(I) is represented by the followingformula(II) :

wherein L represents a substituted or unsubstituted arylene group having6 to 30 ring carbon atoms, m represents an integer of 0 to 6, nrepresents an integer of 0 to 4, p represents an integer of 0 to 4; Aris a substituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, provided that Ar represents a substituted or unsubstituted phenylgroup, a substituted or unsubstituted naphthyl group, a substituted orunsubstituted anthracenyl group, a substituted or unsubstitutedphenanthrenyl group, a substituted or unsubstituted pyrenyl group, and asubstituted or unsubstituted chrysenyl group; R₁ to R₄ are independentlyselected from the group consisting of a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted aryl group having 6 to 30 carbon atoms and a substitutedor unsubstituted heteroaryl group having 3 to 30 carbon atoms.
 4. Thephenanthroline derivative according to claim 3, wherein Ar isrepresented by the following formulas :


5. A organic electroluminescent device comprising a pair of electrodesconsisting of a cathode and an anode and between the pairs of electrodescomprising at least a layer of the phenanthroline derivative with ageneral formula(I) according to claim
 1. 6. The organicelectroluminescent device according to claim 5, wherein the electrontransport layer comprising the phenanthroline derivative with a generalformula(I).
 7. The organic electroluminescent device according to claim5, wherein the hole blocking electron transport layer comprising thephenanthroline derivative with a general formula(I).
 8. The organicelectroluminescent device according to claim 5, wherein the holeblocking layer comprising the following formulas :


9. The organic electroluminescent device according to claim 6, whereinthe electron transport layer comprising lithium or8-hydroxyuinolinolato-lithium.
 10. The phenanthroline derivativeaccording to claim 1, wherein the phenanthroline derivative is selectedfrom the formula consisting of :